Asymmetry of the Atomic Core Structure of Dissociated a‐Screw Dislocation in GaN Probed by Polarization Optical Spectroscopy

Abstract

The a‐screw dislocation related luminescence (DRL) in n‐GaN is investigated with polarization optical spectroscopy. An unusual difference in the polarization directions of two DRL spectral components is observed: directed parallel or inclined at an angle of about 40° to the dislocation line. As a tentative explanation, that property is proposed to be due to the theoretically predicted different orientations of chemical bonds in the cores of N and Ga partials of the dissociated a‐screw dislocation.

Unusual Polarization Dependence of Dislocation‐Related Luminescence in n‐GaN

“…As the electron wave function in triangular part of SF QW is confined close to Ga partial, it overlaps strongly with the p‐like wave function of the hole at the same partial, giving rise to direct transition of the bound exciton, which polarized along the dislocation line due to a strict 1D confinement of electrons and holes. Such type of the transition corresponds to the experimentally observed narrow Lorenz‐shape DRL H line …”

“…A short description of that results was published very recently. [8] The different polarization is explained to be due to an asymmetry of atomic arrangement in the core of dislocations predicted by the theory. [9] In highly dislocated region produced by indentation, DRL H and DRL L lines were significantly broader, and additional new spectral bands appeared by the variation of the polarization of outcoming light emission caused by the presence of two screw dislocation families.…”

“…We found that, for individual dislocations, the spectral component DRL H was directed parallel, whereas DRL L was inclined under the angle of about 40° to the dislocation line. A short description of that results was published very recently . The different polarization is explained to be due to an asymmetry of atomic arrangement in the core of dislocations predicted by the theory .…”

“…Such type of the transition corresponds to the experimentally observed narrow Lorenz-shape DRL H line. [8] The second type of the transition in the band diagram (Figure 5) is between the electron state of SF and N partial shallow hole state. The probability of this transition is defined by the overlapping of the exponential tails of the electron wave function of SF QW confined mostly at Ga partial and the hole wave function of N partial and, thus, strongly depends on the SF ribbon width, d SF .…”